My invention pertains to a railroad traffic control signaling system. More specifically, this invention relates to a railroad signaling system for a stretch of track without wayside signals which provides a special proceed signal indication for trains having inoperative cab signal apparatus and a coordinated traffic direction control circuit to eliminate traffic reversal timing problems.
One simple method of controlling either direction operation over a stretch of track having no wayside intermediate signals, and traversed by trains equipped with cab signal apparatus, is to control the reversible coded track circuits within the stretch by a polarized traffic line circuit. A single track circuit energy source and train detector/track relay set is switched between adjoining track sections at intermediate locations with changes in the traffic direction, thus saving on the total amount of apparatus required. Since traffic relays normally used vary in operating time, one problem encountered with this signaling arrangement is to ensure that all traffic relays reverse during the establishing of a new traffic direction since a release of the decoding relays during track circuit reversal may otherwise lock out the traffic line circuit operation. In other words, some means must be supplied to provide a delay time before the traffic line circuit is deenergized. The use of slow release traffic reversal control relays and control of the traffic relay from the ends of the line circuit provides the necessary time delay. Another problem encountered is the delay which trains having nonoperative cab signal apparatus incur. Without wayside signals, these trains must move at a restricted speed which results in further delays to following or opposing trains and thus a serious interruption of the entire schedule of operation. A solution to this problem is to provide a special signal indication at the last wayside signal control point or interlocking where trains enter the single track stretch. This additional signal, if displayed, designates that a clear block exists to the next control location where a wayside signal is positioned, that the traffic direction is in the proper condition, and that there are no opposing movements authorized or occurring. The train with the inoperative cab signals is then authorized to proceed through the stretch of track without cab signal indications at a predetermined maximum speed limit. Such a block clear or super-clear indication may be provided by an additional line circuit which will simplify the traffic line circuit and thus reduce the total relay requirement for the overall system and at the same time improve its operation.
Accordingly, an object of my invention is a railroad traffic control and signaling system providing an improved operation in reversing the traffic direction.
Another object of the invention is a railroad traffic control and signaling system which provides a special block clear indication to authorize movement of a train with inoperative cab signal apparatus through the controlled stretch of track.
A further object of my invention is a traffic control line circuit, for use in a railroad signaling system, which uses slow release control relays to assure the completion of the traffic reversal procedures without requiring extra timing relays.
Yet another object of the invention is a railroad signaling system with traffic control line circuits which provide an independent clear block indication while yet assuring the completion of the traffic reversal procedures.
A still further object of the invention is a traffic direction control arrangement for a railroad signaling system in which the traffic reversal timing is correlated and controlled external to the actual traffic line circuit arrangement.
It is also an object of my invention to provide an improved traffic direction control arrangement for a railroad signaling system without wayside signals which overcomes traffic reversal timing problems and also provides a clear block indication to authorize train movements through the stretch or signal block when cab signal apparatus is inoperative.
Other objects, features, and advantages of my invention will become apparent from the following specification when taken in connection with the accompanying drawings and the appended claims.